A Path Computation Element (PCE) is a network element that computes communication paths, such as label switched paths, through a computer network. The computed paths are determined based on specified constraints and optimization criteria in light of the PCE's view of the network topology. A stateful PCE maintains information about the network topology as well as network resources utilized by the communication paths established in the network. A stateful PCE then uses this information to compute globally optimal paths.
One-to-one, end-to-end path protected communication paths provide a pre-signaled label switched path over a dedicated resource-disjoint alternate path to protect an associated primary label switched path. Under normal conditions, traffic is forwarded over the primary label switched path while the standby label switched path does not carry any traffic even though resources are bound to it. Upon failure of the primary label switched path, traffic is switched onto the standby label switched path to maintain traffic flow.
When establishing primary and standby label switched paths it is possible to have an imbalance in the distribution of the primary and standby paths on the network. In practice, PCEs may place multiple primary label switched paths on the same path, and the corresponding standby paths on the same disjoint path.
As failures along the primary path are usually rare in a highly available network, the primary traffic will be forwarded on the primary label switched paths for the majority of the time. Given standby label switched paths for one-to-one path protection do not carry any traffic prior to primary label switched path failures, the paths carrying more standby label switched paths become poorly utilized while paths carrying more primary label switched paths may suffer congestion at peek traffic times.